Portable in-situ ozone-generating remedial system

ABSTRACT

Methods and systems are presented for treating groundwater in a groundwater well using one or more portable devices including a body having an air inlet port, an ozone/air mixture outlet port, an ozone generator, and a high-voltage power supply, wherein air from the atmosphere is mixed with ozone generated by the ozone generator and the mixture is expelled into the groundwater well. A diffuser and/or diffusion chamber may be provided with some systems.

This application claims the benefit of U.S. Provisional Application No. 60/813,419, filed Jun. 14, 2006, which is hereby incorporated by reference in its entirety.

Provided are certain systems and methods for the treatment of groundwater, and more specifically, to systems and methods for in-situ decontamination of groundwater by infusing contaminated soil with ozone or an ozone/air mixture.

Groundwater treatment systems may employ chemical oxidation and/or aerobic biodegradation to remove contaminants from subterranean water sources. Contaminated soil may be infused with gas to create an environment suitable for chemical oxidation and/or aerobic biodegradation. Current in-situ groundwater treatment systems are typically large-scale systems that require sophisticated technical expertise to install and maintain, a considerable area on the ground surface to be dedicated to system controllers and other equipment, and a traditional alternating current (AC) electrical power connection to be available at the treatment site. Many current systems require digging in order to access contaminated soil and groundwater or for subterranean placement of treatment equipment.

Provided are certain systems and methods for treating groundwater in a groundwater well. In some embodiments, the system includes a body configured to be disposed below ground level in communication with the groundwater to be treated. The body may include at least one air inlet port for admitting air, at least one ozone/air mixture outlet port, at least one ozone generator positioned inside the body for generating ozone, and at least one high-voltage power supply. The body may be configured to mix the air from the atmosphere with the ozone generated by the ozone generator and expel the ozone/air mixture into the groundwater well through the ozone/air mixture outlet port.

In some embodiments, a method of treating groundwater in-situ at a remedial location below ground level in a groundwater well may include installing at the location a body having an ozone generator, a high-voltage power supply operatively connected to the ozone generator, an air inlet for admitting air, and at least one ozone/air mixture outlet. The method may further include supplying power to the high-voltage power supply from an electrical power source, powering the ozone generator using the high-voltage power supply, and generating ozone using the ozone generator. The method may further include flowing air from the air inlet through the system past the ozone generator to create an ozone/air mixture, and channeling the ozone/air mixture into the remedial location.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a detailed sectional view of an exemplary system for in-situ treatment of groundwater.

FIGS. 2A and 2B show cross-sectional views of two further exemplary systems for in-situ treatment of groundwater.

FIG. 3 shows an oblique view of an exemplary rectangular cold-corona discharge ozone generator.

FIG. 4 shows a cross-sectional view looking down the center-axis of an exemplary cylindrical cold-corona discharge ozone generator.

FIGS. 5A and 5B show cross-sectional views of two other exemplary systems for in-situ treatment of groundwater.

FIG. 6 shows an environmental view of an exemplary system deployed in a groundwater well.

FIG. 7 shows an environmental view of an exemplary system deployed in a groundwater well with a solar power source.

Reference will now be made in detail to one or more exemplary embodiments of the present invention as illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

FIG. 1 shows a detailed sectional view of an exemplary system 100 for in-situ treatment of groundwater. In some embodiments, system 100 includes a single hollow body 23. In some embodiments, as shown in FIG. 1, body 23 may be cylindrical, but other cross-sectional shapes are possible. In some embodiments, system 100 is closed off at one or both ends by an end cap 26. Body 23 may be constructed of any non-conducting material, such as PVC, acrylic, or another plastic material. In some embodiments, end cap 26 is made of the same material as body 23. In some embodiments, end cap 26 is made of a different non-conducting material than body 23. With continued reference to FIG. 1, body 23 may include one or more chambers or zones such as inlet chamber 43, power supply chamber 44, and ozone generator chamber 45. Chambers or zones of body 23 may be separated or divided by one or more chamber dividers 24, as depicted in FIG. 1. Chamber divider 24 may be made of PVC, acrylic, another plastic material, or any air-impervious material. In some embodiments, body 23 may not be divided into separate chambers.

In some embodiments, air enters an inlet chamber 43 through one or more air inlet ports 3, which may be located in an end cap 26 as depicted in FIG. 1. Air may be drawn into inlet chamber 43 by an air pump 5. In some embodiments, air pump 5 may have a pressure range between 0 and 24 pounds per square inch (PSI), with a max unrestricted flow rate between 1.8 and 2.5 liters per minute (LPM). In some embodiments, air pump 5 may be a Hargrave Advanced Fluidic Solutions CTS series pump, or a Smart Product, Inc., model #AP-3P01, or similar air pump.

In some embodiments, air is drawn directly into inlet chamber 43 by air pump 5, as shown in FIG. 1. In some embodiments, such as systems 300 and 400, shown in FIGS. 5A and 5B (discussed in detail below), air may pass from an air source (not shown) through an air supply tube 21 not shown to air inlet port 3, and then to air pump 5. In the depicted embodiments, air is thereafter pumped from air pump 5 into air injection tube 6. In some embodiments, air supply tube 4 and/or air injection tube 6 is made of silicone. In some embodiments, air supply tube 4 and/or air injection tube 6 may be made of any plastic, rubber, or other air-impervious material. In some embodiments, air is pumped through air injection tube 6 into an ozone generator chamber, such as generator chamber 45.

Ozone generator chamber 45 may house a cold-corona discharge ozone generator 9A or 9B (discussed in detail below and shown in FIGS. 2A, 2B, 3 and 4). Ozone is generated at ozone generator 9A or 9B and mixes with the air that has been pumped into ozone generator chamber 45. This ozone/air mixture may then be forced out of system 100 into the surrounding groundwater through one or more ozone/air injection ports, such as injection port 10, which may be disposed in an end cap 26. The operation of cold-corona discharge ozone generator 9A or 9B is discussed in further detail below in reference to FIGS. 3 and 4. In some embodiments, groundwater is circulated by a water circulation pump 18 (shown at FIG. 6 and discussed below) for the purpose of more effective remediation of a remedial zone 22 (shown at FIG. 6 and discussed below).

With continued reference to FIG. 1, system 100 may be connected to a power source (not shown) by line cord 2. In some embodiments, line cord 2 extends to a power source located above ground surface. In some embodiments, line cord 2 may be connected to a battery housed within body 23 or elsewhere. In some embodiments, a low-voltage DC power supply at 12 volts is sufficient to support operation of system 100. In some embodiments, the power source may be a generator or a solar panel or array. In some embodiments, the power source may be a rectified AC power source. In some embodiments, line cord 2 may also power air pump 5.

System 100 may include a high-voltage electrical power supply 7 for powering ozone generator 9A or 9B. In some embodiments, line cord 2 couples to and powers high-voltage electrical power supply 7. In some embodiments, high-voltage power supply 7 is connected to ozone generator 9A or 9B via high-voltage line cord 8, which may, for example, be made from a stainless steel conductor and have an 8 K volt rating. In some embodiments, high-voltage power supply 7 may be a high-voltage power supply converter such as Yui Da Electrics Co., Ltd. model YD-01S, or similar, and may include resistor 25 connected to the high-voltage power supply to adjust max voltage range and drive frequency. High voltage power supply may include resistor 25 that may be 5 watts and 10 K ohms, to produce max voltage of 7,000 volts AC current. In some embodiments, resistor 25 may be an NTE model #5 W310, or equivalent.

FIGS. 2A and 2B show cross-sectional views of two further exemplary systems 200 and 200′ for in-situ treatment of groundwater. Systems 200 and 200′ are similar to in structure and operation to system 100, except that systems 200 and 200′ do not include an air pump 5 or inlet chamber 43. Instead, air is forced directly into air injection tube 6 through air inlet port 3, for example as by an external pressurized air source (not shown) which may be located above ground surface. As in system 100, air may enter ozone generator chamber 45 through air injection tube 6, where it mixes with ozone produced by ozone generator 9A or 9B and the air/ozone mixture exits system 200 through ozone/air injection port 10. In some embodiments, systems 200 and 200′ may further include one or more ozone generator support spacers, such as spacer 27 shown in system 200 in the FIG. 2A embodiment. Support spacer 27 may be perforated to allow air flow through the chamber. Support spacer 27 may be made of Delrin® or any electrically insulating, ozone-resistant material suitable for holding ozone generator 9A or 9B in place. FIG. 2A shows an exemplary system 200 including a cylindrical cold-corona discharge ozone generator, which may be of the type shown as 9B in FIG. 4. FIG. 2B shows an exemplary system 200′ including a rectangular cold-corona discharge ozone generator, which may be of the type shown as 9A in FIG. 3.

FIG. 3 shows an oblique, detailed view of an exemplary rectangular cold-corona discharge ozone generator 9A having a series of parallel plate-shaped electrodes 28. In some embodiments, parallel electrodes 28 may be connected in alternating polarity to high voltage line 8. Parallel electrodes 28 may be separated by dielectric plates 29 to prevent sparking between parallel electrodes 28. Electrodes 28 may be stainless steel screens with 500 micron mesh. In some embodiments, electrodes 28 may be constructed of any corrosion-resistant conductor. Dielectric plates 29 may be glass. In some embodiments, dielectric plates 29 may be any dielectric or nonconducting material suitable for high-voltage operation.

In some embodiments, ozone generator 9A may be configured to include one or more frame members such as cap 30. Cap 30 may be configured to hold dielectric plates 29 in place. In some embodiments, cap 30 may be made of PVC or any non-conducting material. In some embodiments, cap 30 may be slotted to hold dielectric plates 29. In some embodiments, dielectric plates 29 may be secured to cap 30 with type II silicone sealant.

When high voltage current is applied to the cold-corona discharge ozone generator 9A, a corona (electrical discharge) is produced by an electric charge between the parallel electrodes 28. At least some of the oxygen molecules contained within the air passing between electrodes 28 and dielectric plates 29 may be split by the corona into oxygen atoms. Some of the oxygen atoms may recombine again to form molecular oxygen, but some of the oxygen atoms combine to form ozone. The air in ozone generator chamber 45 (discussed above in relation to FIG. 1) combines with the ozone and the mixture flows out of ozone generator chamber 45 as discussed above. Cold-corona discharge ozone generator 9A and 9B may produce between 0.375 and 0.5 grams of ozone per cubic meter of air, respectively, or 1 gram of ozone per day at a max air flow rate of 1.8 LPM up to 16 grams per day at a max air flow rate of 17.85 LPM utilizing ozone generator 9B.

FIG. 4 shows a cross-sectional view looking down the center axis of exemplary system 200′ including a cylindrical cold-corona discharge ozone generator, such as ozone generator 9B. Cold-corona discharge ozone generator 9B includes an outer cylindrical electrode 31 a surrounding a cylindrical dielectric 32. Contained within the dielectric is a second cylindrical electrode 31 b. Electrodes 31 a and 31 b may be stainless steel screens with 500 micron mesh. In some embodiments, electrodes 31 a and 31 b may be constructed of any corrosion-resistant conductor, such as noble and/or transitional metals. Between outer electrode 31 a and dielectric 32 is a narrow gap 47, through which air passes. Ozone generator 9B works on the same scientific principles discussed above with reference to ozone generator 9A. Ozone generator 9B includes cylindrical electrodes 31 on the outside and inside of a cylindrical dielectric 32. One or more cylindrical electrode may be contained within the dielectric 32 in some embodiments. Dielectric tube 32 may be borosilicate glass. As discussed above, a support spacer such as spacer 27 may be perforated with holes 48 and hold ozone generator 9B in place within body 23. Electrical connection apparatus 33 may connect ozone generator 9B to high-voltage lines 8 (discussed above; not shown here). In some embodiments, connection apparatus 33 may include a bolt, a nut, and one or more washers or similar electrical fasteners.

FIGS. 5A and 5B show cross-sectional views of two more exemplary systems 300 and 400, respectively, for in-situ treatment of groundwater. Both systems 300 and 400 are similar in most details to system 100 described above with reference to FIG. 1, and operate on the same basic principles as system 100. Both systems 300 and 400 differ from system 100 in that systems 300 and 400 are not divided into separate chambers. Both systems 300 and 400, however, include an air supply tube 4 coupled at one end to air inlet port 3 and at the other end to air pump 5, through which air passes from inlet port 3 into air pump 5. Systems 300 and 400 may further include air delivery tubes to carry air from pump 5 to ozone generator 9. In some embodiments, ozone generator 9 may be a Yui Da Electrics Co., Ltd. YD-06 series ozone generator, or similar ozone generator.

In systems 300 and 400, the ozone/air mixture may exit the cold-corona discharge ozone generator 9 and pass through appropriate ducting, such as ozone/air injection tube 10 to a check valve such as check valve 11. The check valve 11 allows the one-way flow of the ozone/air mixture to a diffuser 12, but prevents groundwater from passing through diffuser 12 into the cold-corona discharge ozone generator 9. Check valve 11 can be an ozone-safe duckbill type for above-water use, or any ozone safe pressure valve type for in-water use. Diffuser 12 may be formed of microporous polyethylene, glass-bonded silica, or similar ozone-tolerant porous material.

With reference to FIG. 5A, system 300 may further include a diffusion chamber, such as diffusion chamber 46, which houses diffuser 12. In some embodiments, the ozone/air mixture passes through the diffuser 12 and into a chamber at the base of the device. In some embodiments, the walls of diffusion chamber 46 may be formed of a groundwater filter 13, such as a microporous polyethylene tube. The ozone/air mixture dissolves into groundwater entering diffusion chamber 46. The embodiment of system 300 may further include a separate water pump 18 (discussed below; not shown here) located in the groundwater well below system 300. In some embodiments, water pump 18 may be connected to system 300 via an ozone/air/water outlet port 14. The ozone/air/water mixture may be drawn into diffusion chamber 46 through filter 13, and then from the diffusion chamber 46 through outlet port 14A to the water pump 18, which discharges the mixture to the contaminated soil and groundwater surrounding the groundwater well. In the embodiment of system 400 (FIG. 5B), no separate diffusion chamber is provided such that the ozone/air mixture may enter the groundwater well directly after passing through a diffuser, such as diffuser 12, which can be affixed to the outlet of check valve 11, where the mixture dissolves into surrounding groundwater.

FIG. 6 shows an environmental view of an exemplary system deployed in a groundwater well. FIG. 6 shows an exemplary system 300, as discussed above and shown in FIG. 5A, deployed in a groundwater well 15. The base of system 300 may be positioned in the groundwater well 15 below the water table 16. A water circulation pump 18 may be positioned in groundwater well 15 at a suitable distance below system 300. System 300 and water circulation pump 18 are connected through line cord 2 and ozone/air/water supply tube 17. Low voltage DC power may be supplied to system 300 by the line cord 2, and air may be supplied to system 300 by an air supply tube 21 from above ground surface. System 300 and water circulation pump 18 may be held in place in the well by the weight of bob 19, which may be coupled to either system 300 or pump 18.

The ozone/air mixture produced by system 300 may be pumped from system 300 into groundwater, or the ozone/air/water mixture may be pumped by water circulation pump 18 into the soil and groundwater surrounding the groundwater well, into remedial zone 22. Contaminants contained in remedial zone 22 that encounter the dissolved ozone/air (ozone/air/water) mixture are broken down into less harmful compounds, remediating the contaminated soil and groundwater. The action of extracting groundwater from groundwater well 15 at the base of the device, and pumping it through water circulation pump 18, creates a circulating zone of groundwater surrounding the groundwater well, further facilitating remediation.

In some embodiments, the groundwater flow direction may be reversed, such that the operation of water pump 18 may cause groundwater to be pumped into the diffusion chamber 46 at the base of the device 300 through outlet port 14. The ozone/air mixture produced by the device, and flowing through diffusion chamber 46, would dissolve into the supplied groundwater, and then pass from the device through groundwater filter 13 into the contaminated soil and groundwater surrounding the groundwater well.

FIG. 7 shows an exemplary system, e.g. system 200 shown in FIG. 2 and discussed above, configured to operate above ground surface. Low voltage direct current power may be produced by solar power source 20, which may be, e.g., a 150-watt solar panel. In some embodiments, the power source may be any external power supply connected to, for example, a generator or existing electrical utilities at the remediation site.

System 200 may be housed within cabinet 34 and coupled to air inlet port 40, through which air may enter system cabinet 34. In some embodiments, system 200 may be deployed in groundwater well 15 below water table 16. In some embodiments, cabinet 34 may be a locking, weather-resistant cabinet supported by support pole 35, which is driven into the ground. In some embodiments, cabinet 34 may include a battery 41 connected to a charge controller 37 (e.g. of 250 watt capacity), timer 38, and compressor 39. In some embodiments, Charge controller 37 may facilitate proper charging of battery 41 by controlling the storage of solar power in battery 41. Timer 38 may be set to control the operating times of system 200. In some embodiments, timer 38 may be configured to pulse remedial action operating times of system 200. In some embodiments, timer 38 may not be present. During operation, compressor 39 may pump air from outside cabinet 34, through air inlet port 40, and into system 200. The electrical components of the embodiment shown in FIG. 7 may be connected to a power source via line cord 2.

In some embodiments, compressor 39 may operate between 10.5 and 17.85 LPM and may be of a 12-volt DC piston type similar to Grainger models 5BB70, 5Z349, or 5KA74. In some embodiments, compressor 39 may produce between 9.4 and 16 grams of ozone per day. In some embodiments, battery 41 may be a 12 volt, 110 amp-hour battery.

Air supply tube 21 extends from above ground surface inside well 15, and may connect to packer 42. Diffuser 12 may be coupled to packer 42. The air/ozone mixture created at system 200 may be pumped through air supply tube 21, through packer 42, and out diffuser 12 into groundwater. In some embodiments, packer 42 may be constructed of Viton® or silicone.

Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. It is intended that the specification and examples be considered as exemplary only, and not an exhaustive list of every combination of features that may comprise the invention described herein. 

1. Apparatus for treating groundwater in a groundwater well, the apparatus being powered from an electrical power source, the apparatus comprising: a body configured to be disposed below ground level in communication with the groundwater to be treated, the body including: at least one air inlet port for admitting air; at least one ozone/air mixture outlet port; at least one ozone generator positioned inside the body for generating ozone; and at least one high-voltage power supply, connectable to the electrical power source, for powering the at least one ozone generator; wherein the body is configured to mix the air from the atmosphere with the ozone generated by the ozone generator and expel the ozone/air mixture into the groundwater well through the ozone/air mixture outlet port.
 2. The apparatus as in claim 1, wherein the body includes an ozone generator chamber, the system further comprising an air injection tube interconnected between the air inlet port and the ozone generator chamber, the ozone generator chamber housing the ozone generator.
 3. The apparatus as in claim 1, wherein the body is portable.
 4. The apparatus as in claim 1, wherein the ozone generator is a rectangular cold-corona discharge ozone generator.
 5. The apparatus as in claim 1, wherein the ozone generator is a cylindrical cold-corona discharge ozone generator.
 6. The apparatus as in claim 1, further including a resistor operatively connected to the high-voltage power supply to provide max voltage.
 7. The apparatus as in claim 1, further comprising a first line cord that electrically connects the electrical power source to the high-voltage power supply.
 8. The apparatus as in claim 7, further comprising a second line cord that electrically connects the high-voltage power supply to the ozone generator.
 9. The apparatus as in claim 1, further comprising a diffuser for diffusing the ozone/air mixture into the groundwater well.
 10. The apparatus as in claim 9, wherein the body further includes a diffusion chamber for housing the diffuser.
 11. The apparatus as in claim 10, wherein at least one wall of the diffusion chamber is made of a groundwater filter material.
 12. The apparatus as in claim 10, wherein the diffusion chamber is configured to admit groundwater for mixing with the ozone/air mixture, forming an ozone/air/groundwater mixture.
 13. The apparatus as in claim 1, wherein the body further includes an air pump for drawing air into the air inlet port.
 14. The apparatus as in claim 13, further comprising a first line cord that electrically connects the electrical power source to the air pump.
 15. An in-situ groundwater treatment system for treating groundwater in a groundwater well, the system comprising: a body having at least: an electrical power source located at or above ground surface; an air inlet port for admitting air; an ozone/air mixture outlet for expelling an ozone/air mixture into the groundwater well; an ozone generator positioned inside the body for generating ozone; and at least one high-voltage power supply for powering the ozone generator, and being operatively connected to the electrical power source; wherein the air from the air inlet combines with the ozone generated by the ozone generator and the ozone/air mixture is expelled into the groundwater well through the ozone/air mixture outlet.
 16. The system as in claim 15, wherein the body is configured to be disposed below ground level in the groundwater well.
 17. The system as in claim 15, further comprising a water circulation pump for circulating groundwater in a remedial area, wherein the water circulation pump is disposed below ground level in communication with the groundwater to be treated.
 18. The system as in claim 17, wherein the pump is powered by the electrical power source.
 19. The system as in claim 16, further comprising an air line connected to the air inlet for providing air from the atmosphere, and an air injection tube interconnecting the air inlet to an ozone generator chamber, the ozone generator chamber housing the ozone generator.
 20. The system as in claim 15, wherein the system is portable.
 21. The system as in claim 15, wherein the ozone generator is a rectangular cold-corona discharge ozone generator.
 22. The system as in claim 15, wherein the ozone generator is a cylindrical cold-corona discharge ozone generator.
 23. The system as in claim 15, further including a resistor connected in parallel with the high-voltage power supply.
 24. The system as in claim 15, wherein the body is located above ground surface; and further comprising an ozone/air supply tube for supplying an ozone/air mixture to the groundwater well.
 25. The system as in claim 15 wherein the power source is a low-voltage power source and comprises at least one of: a direct current (DC) power source; a solar cell; a solar array; a battery; an electrical generator; and a rectified alternating current (AC) power source.
 26. The system as in claim 15, further comprising a first line cord that electrically connects the electrical power source to the high-voltage power supply.
 27. The system as in claim 26, further comprising a second line cord that electrically connects the high-voltage power supply to the ozone generator.
 28. The system as in claim 15, further comprising a diffuser for diffusing the ozone/air mixture into the groundwater well.
 29. The system as in claim 28, wherein the body further includes a diffusion chamber for housing the diffuser.
 30. The system as in claim 29, wherein at least one wall of the diffusion chamber is made of a groundwater filter material.
 31. The system as in claim 29, wherein the body is configured to admit groundwater into the diffusion chamber for mixing with the ozone/air mixture to form an ozone/air/groundwater mixture.
 32. The system as in claim 31, wherein the diffusion chamber includes an ozone/air/groundwater outlet through which the ozone/air/groundwater mixture exits the system and enters the groundwater well.
 33. The system as in claim 15, further comprising an air pump for providing air to the groundwater treatment system through the air inlet.
 34. The system as in claim 33, wherein the air pump is disposed within the body, and wherein the system further comprises a first line cord that electrically connects the electrical power source to the air pump.
 35. The system as in claim 15, wherein the body is housed in a cabinet above ground surface.
 36. The system as in claim 35 wherein the cabinet further houses an air compressor coupled to the air inlet of the body.
 37. The system as in claim 35, wherein the cabinet further houses a timer for controlling the operating times of the system.
 38. The system as in claim 35, further comprising a charge controller and a battery, wherein the charge controller manages the storage of energy in the battery and the battery is coupled to the electrical power source.
 39. A method of treating groundwater in-situ at a remedial location below ground level in a groundwater well, the method comprising: installing at the location a body having an ozone generator, a high-voltage power supply operatively connected to the ozone generator, an air inlet for admitting air, and at least one ozone/air mixture outlet; supplying power to the high-voltage power supply from an electrical power source; powering the ozone generator using the high-voltage power supply; generating ozone using the ozone generator; flowing air from the air inlet through the system past the ozone generator to create an ozone/air mixture; and channeling the ozone/air mixture into the remedial location.
 40. The method as in claim 39, further comprising circulating water in the remedial location using a water circulation pump.
 41. The method as in claim 39, wherein supplying power includes locating an electrical power source above ground surface and electrically connecting the electrical power source to the high-voltage power supply via a first line cord.
 42. The method as in claim 41, wherein powering the ozone generator includes electrically connecting the ozone generator to the high-voltage power supply via a second line cord.
 43. The method as in claim 39, further comprising diffusing the ozone/air mixture into the groundwater well.
 44. The method as in claim 39, further comprising mixing groundwater with the ozone/air mixture, forming an ozone/air/groundwater mixture.
 45. The method as in claim 44, further comprising expelling the ozone/air/groundwater mixture from the system into the groundwater well through a ozone/air/groundwater mixture outlet port.
 46. The method as in claim 39, further comprising pumping air through the body including past the ozone generator. 